Wireless module

ABSTRACT

A wireless device that suppresses deterioration of antenna characteristics and can be made thin is provided. The wireless device is provided with a substrate, a wireless module that is mounted on the substrate and has an antenna unit, and a casing that accommodates the substrate and the wireless module. The wireless device has a gap of a length that is an approximate multiple of a half-wavelength of a radio wave corresponding to a communication frequency of the antenna unit, from the antenna unit toward the casing.

TECHNICAL FIELD

The present disclosure relates to a wireless module.

BACKGROUND ART

In wireless devices in which an antenna-equipped wireless module isstored inside a casing, antenna characteristics sometimes deteriorate.In order to improve antenna characteristics, the following antennas areknown. For example, a microstrip antenna that has a dielectric adheredto an antenna surface is known (for example, see PTL 1). Furthermore, anantenna device which has a radome that maintains a space in a constantmanner between a radiation element and interior glass, which correspondsto a casing, is known (for example, see PTL 2).

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2005-244742

PTL 2: Japanese Unexamined Patent Application Publication No.2007-097084

SUMMARY OF INVENTION Technical Problem

In the technology of PTL 1 and 2, it was difficult to suppressdeterioration of antenna characteristics and to make the wireless devicethin.

An embodiment of the present disclosure takes the aforementionedcircumstances into consideration and provides a wireless device thatsuppresses deterioration of antenna characteristics and can be madethin.

Solution to Problem

A wireless device in an embodiment of the present disclosure comprises asubstrate, a wireless module that is mounted on the substrate and has anantenna unit, and a casing that accommodates the substrate and thewireless module. The wireless device has a gap from the antenna unittoward the casing, and the gap has a length that is an approximatemultiple of a half-wavelength of a radio wave corresponding to acommunication frequency of the antenna unit.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, deterioration ofantenna characteristics is suppressed and thinning can be implemented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view depicting a first exemplary structureof a wireless device in a first embodiment.

FIG. 2 is a schematic view depicting an example of the relationshipbetween clearance and radio wave intensity in the first embodiment.

FIG. 3 is a cross-sectional view depicting a second exemplary structureof the wireless device in the first embodiment.

FIG. 4 is a cross-sectional view depicting a third exemplary structureof the wireless device in the first embodiment.

FIG. 5 is a cross-sectional view depicting a fourth exemplary structureof the wireless device in the first embodiment.

FIG. 6 is a cross-sectional view depicting a fifth exemplary structureof the wireless device in the first embodiment.

FIG. 7 is a schematic view depicting an example of the relationshipbetween the size of an opening in the wireless device and radio waveintensity in the case of the fourth exemplary structure or the fifthexemplary structure in the first embodiment.

FIG. 8 is a schematic view depicting the smallest opening size in thecase where the shape of the opening in the wireless device in the fourthexemplary structure or the fifth exemplary structure in the firstembodiment is square.

FIG. 9 is a schematic view depicting the smallest opening size in thecase where the shape of the opening in the wireless device in the fourthexemplary structure or the fifth exemplary structure in the firstembodiment is rectangular.

FIG. 10 is a cross-sectional view depicting a first exemplary structureof a wireless device in a second embodiment.

FIG. 11 is a cross-sectional view and a plan view depicting a secondexemplary structure of the wireless device in the second embodiment.

FIG. 12 is a cross-sectional view and a plan view depicting a firstexemplary structure of a wireless device in a third embodiment.

FIG. 13 is a cross-sectional view and a plan view depicting a secondexemplary structure of the wireless device in the third embodiment.

FIG. 14 is schematic views depicting an example of a radio waveradiation pattern according to an antenna in the case of the secondexemplary structure of the third embodiment.

FIG. 15 is a schematic view for illustrating conical plane directivityin the third embodiment.

FIG. 16 is a cross-sectional view and a plan view depicting a firstexemplary structure of a wireless device in a fourth embodiment.

FIG. 17 is a cross-sectional view and a plan view depicting a secondexemplary structure of the wireless device in the fourth embodiment.

FIG. 18 is a cross-sectional view and a plan view depicting a thirdexemplary structure of the wireless device in the fourth embodiment.

Hereinafter, embodiments of the present disclosure are described usingthe drawings.

(Circumstances Leading to Obtaining an Embodiment According to thePresent Disclosure)

In the technology of PTL 1, when there is a manufacturing error, thereare cases where the dielectric does not adhere to the antenna surface,and the antenna characteristics deteriorate. Furthermore, there is apossibility of deviation occurring in the attachment position due to themanufacturing error, stress being applied to the module and the casing,and the module or the casing breaking.

In the technology of PTL 2, the thickness of an air layer between aradiation element and a ground plate is a length that is given incentimeter units, and additionally has a radome, and it is thereforedifficult to make the wireless device thin.

Hereinafter, a description is given with respect to a wireless devicethat suppresses deterioration of antenna characteristics and can be madethin.

(First Embodiment)

FIG. 1 is a cross-sectional view depicting a wireless device 1 as afirst exemplary structure of a wireless device in the first embodiment.The wireless device 1 includes a wireless module 10, a substrate (setsubstrate 20) on which the wireless module 10 is mounted, and a casing(set casing 30) in which the wireless module 10 and the set substrate 20are accommodated.

Here, the plane parallel to the surface of a module substrate 3 is theX-Y plane, and, in FIG. 1, the horizontal direction is the X directionand the depth direction is the Y direction. Furthermore, the directionperpendicular to the surface of the module substrate 3, namely thedirection perpendicular to the X-Y plane, is the Z direction.

The wireless module 10 includes the module substrate 3, on whichantennas 13 are mounted on one surface. The module substrate 3 isformed, for example, in a rectangular plate shape, and is a multilayersubstrate that includes, for example, seven metal layers 3 a and adielectric layer 3 b filled between the metal layers 3 a. The antennas13, which are made up of, for example, 2×2 (four) patch antennas, areformed on the uppermost layer of the module substrate 3. Furthermore, aground (GND) pattern 11 is formed on the uppermost layer of the modulesubstrate 3.

LSIs 8 and 9 are mounted on the lowermost layer of the module substrate3 with pads 21 a to 21 d and solder balls 22 a to 22 d between the LSIs8 and 9 and the module substrate 3. A mold section 27 in which, forexample, resin has been filled is formed between the LSIs 8 and 9 andthe lower surface of the module substrate 3 in such a way as to coverthe pads 21 a to 21 d and the solder balls 22 a to 22 d.

The position of the LSI 8 in the X direction is, for example,substantially the same as the position of the antennas 13. The LSI 8includes, for example, a high-frequency (RF: radio frequency) IC(integrated circuit) that processes microwave signals transmittedbetween the LSI 8 and the antennas 13. The antennas 13 are connected tothe LSI 8 by way of a signal via 17 that is connected to a wiring layer3 d, the wiring layer 3 d, a signal via 36 that is connected to thewiring layer 3 d and the pad 21 a, the pad 21 a, and the solder ball 22a.

The position of the LSI 9 in the X direction is, for example,substantially the same as the position of the GND pattern 11. The LSI 9includes, for example, a baseband IC that processes a baseband signal.The GND pattern 11 is connected to a GND of the LSI 9 by way of a GNDvia 19 that is connected to a GND layer 3 c, the GND layer 3 c, a GNDvia 33 that is connected to the GND layer 3 c and the pad 21 c, the pad21 c, and the solder ball 22 c.

It should be noted that, in the following exemplary structures and otherembodiments, the configuration of the wireless module 10 may be the sameor may be different.

The set substrate 20 is, for example, a multilayer substrate. There isat least a GND (ground conductor) on the mounting surface of the setsubstrate 20, and a GND of the set substrate 20 and the GND layer 3 c ofthe wireless module 10 have substantially the same potential.

The set casing 30 accommodates the wireless module 10 and the setsubstrate 20, and is formed from, for example, an ABS resin.

The set casing 30 is arranged above (Z-axis positive direction) theantennas 13 of the wireless module 10, and a gap 40 is provided betweenthe set casing 30 and the antennas 13. When the wavelength of a radiowave radiated from the antennas 13 is taken as λ, the gap 40 has alength that is an approximate multiple of 1/2 of the wavelength λ, forexample. The wavelength λ corresponds to the communication frequency ofthe antennas 13.

As a specific example, an approximate multiple of λ/2 is, when theZ-direction length of the gap 40 is the smallest, λ×(3/8) ≦ theZ-direction length of the gap 40≦λ×(5/8), for example. Furthermore, aspace in which the Z-direction length of the gap 40 is small subsequentto the case of approximately (1/2) of the wavelength λ is the case ofapproximately λ(=(λ/2)×2), and is λ×(7/8)≦the Z-direction length of thegap 40≦λ×(9/8), for example.

FIG. 2 is a schematic view depicting an example of the relationshipbetween the Z-direction length (clearance) of the gap 40 and theintensity (relative value) of radio waves radiated by the antennas 13.In FIG. 2, the radio wave intensity under the condition of a resinmember (for example, the set casing 30) not being present opposite thewireless module 10 is taken as a reference (0 dB), and the radio waveintensity with respect to each clearance is indicated by a relativevalue. This radio wave intensity indicates the radio wave intensity inpositions (Z-axis positive side with respect to the antennas 13)opposing the antennas 13.

When reference is made to FIG. 2, it can be understood that the radiowave intensity increases when the clearance is approximately λ/2 orapproximately λ, and that a satisfactory radio wave intensity isobtained when there is a clearance of a prescribed range that includesapproximately λ/2 or approximately λ.

In this way, the wireless device 1 has a gap 40 of a length that isapproximately λ×(1/2)×n (natural number), between the antennas 13 andthe set casing 30 here, from the antennas 13 to the set casing 30 side.In other words, the Z-direction length of the gap 40 is a length that isan approximate multiple of a half-wavelength of a radio wave. Thus, itis possible to reduce the effect on antenna characteristics by thereflection of radio waves in the set casing 30, and it is possible tosuppress changes in the radiation pattern (for example, gain anddirectivity) of the antennas 13. Furthermore, the gap 40 can be ensuredwithout providing a separate member (for example, a radome), andtherefore thinning can be implemented.

FIG. 3 is a cross-sectional view depicting a wireless device 1A as thesecond exemplary structure of the wireless device in the firstembodiment. In FIG. 1, the set casing 30 was formed from a uniformmaterial; however, in FIG. 3, an antenna-opposing region 31 in a setcasing 30A that opposes the antennas 13 may be formed from a differentmaterial from another region 32 in the set casing 30A. As the differentmaterial, for example, a material having a lower relative permittivity,or a material having a smaller tan δ, than the other region 32 is used.The other region 32 is an example of a non-antenna-opposing region.Thus, it is possible to reduce the loss of radio waves when a set casingis added.

For example, dielectric loss per unit length in a material having a lowrelative permittivity or a material having a small tanδ is90.9×√(∈r)×tanδ×f (GHz) [dB/m]. Here, ∈r is the relative permittivity,and f is the communication frequency used by the antennas 13.

The other region 32 in the set casing 30A is, for example, formed froman ABS resin. The antenna-opposing region 31 in the set casing 30A is,for example, formed from a polymethacrylimide hard foam body (forexample, ROHACELL (registered trademark)) or polytetrafluoroethylene(for example, Teflon (registered trademark)).

Furthermore, the size of the antenna-opposing region 31 in the X-Y planeis the same of the size of a recess 37 described hereinafter.

In this way, the wireless device 1A has a gap of a length ofapproximately λ×(1/2)×n, between the antennas 13 and the set casing 30A,and the antenna-opposing region 31 is formed from, for example, amaterial having a lower relative permittivity, or a material having asmaller tanδ, than the other region 32. Thus, the effect on antennacharacteristics caused by the passage of radio waves in the set casing30A can be further reduced.

FIG. 4 is a cross-sectional view depicting a wireless device 1B as athird exemplary structure of the wireless device in the firstembodiment. The wireless device 1B has a plurality of set casings. Afirst set casing 30B1 corresponds to the aforementioned set casing 30and is, for example, a main body cover for the wireless device 1B. Asecond set casing 30B2 (an example of a first member) is, for example, abattery cover and is formed from, for example, a resin. In the casewhere the distance between the antennas 13 and the second set casing30B2 is an approximate multiple of 1/2 of the wavelength λ, the wirelessdevice 1B may have two or more casings.

According to the wireless device 1B, deterioration of antennacharacteristics can be suppressed even when there is a plurality of setcasings.

FIG. 5 is a cross-sectional view depicting a wireless device 1C as afourth exemplary structure of the wireless device in the firstembodiment. The wireless device 1C is a modified example of the wirelessdevice 1B. In the wireless device 1C, for the case where the distancebetween the antennas 13 and the second set casing 30B2 is not anapproximate multiple of 1/2 of the wavelength λ, an opening 34 isprovided in a region in the second set casing 30B2 that opposes theantennas 13. The distance between the antennas 13 and the first setcasing 30B1 is, for example, an approximate multiple of 1/2 of thewavelength λ.

FIG. 6 is a cross-sectional view depicting a wireless device 1D as afifth exemplary structure of the wireless device in the firstembodiment. The wireless device 1D is provided with an electromagneticshield 35 (an example of the first member) that has an opening 35 a in aregion opposing the antennas 13, between the wireless module 10 and theset casing 30B1. For example, the distance between the antennas 13 andthe electromagnetic shield 35 is not an approximate multiple of 1/2 ofthe wavelength λ, and the distance between the antennas 13 and the setcasing 30B1 is an approximate multiple of 1/2 of the wavelength λ.

FIG. 7 is a schematic view depicting an example of the relationshipbetween the size (opening size) of the openings 34 and 35 a in the X-Yplane in the case of the wireless device 1C or the wireless device 1Dand the radio wave intensity (relative value) of radio waves radiated bythe antennas 13. In FIG. 7, the radio wave intensity under the conditionof a resin member (for example, the second set casing 30B2) not beingpresent opposite the wireless module 10 is taken as a reference (0 dB),and the radio wave intensity with respect to each opening size isindicated by a relative value. This radio wave intensity indicates theradio wave intensity in positions (Z-axis positive side with respect tothe antennas 13) opposing the antennas 13.

Furthermore, FIG. 7 depicts the case where a distance d1 (see FIG. 5 andFIG. 6) between the wireless module 10 and the second set casing 30B2 orthe electromagnetic shield 35 is 1 mm. In this case, the length A (seeFIG. 5 and FIG. 6) of one side of the openings 34 and 35 a is asfollows, for example.A=10×sin(θ1/2)/sin(90−θ1/2)×d1

It should be noted that “θ1” indicates the angle range in which the gainof the antennas 13 obtained when not placed in the set casing 30B1becomes approximately 1/4.

FIG. 8 is a schematic view depicting the smallest opening size Amin inthe case where the shape of the openings 34 and 35 a is square. In thecase where the shape of the openings 34 and 35 a is square, thecondition of A≧λ+antenna size W is satisfied.

FIG. 9 is a schematic view depicting the smallest opening sizes ASminand ALmin in the case where the shape of the openings 34 and 35 a isrectangular. In the case where the shape of the openings 34 and 35 a isrectangular, the condition of the short side length AS≧λ+antenna size WSis satisfied, and the condition of the long side length AL≧λ+antennasize WL is satisfied.

When reference is made to FIG. 7, it can be understood that the radiowave intensity becomes the greatest when the openings 34 and 35 a are 10mm (X-direction length)×10 mm (Y-direction length). Consequently, theopenings 34 and 35 a are formed in a square shape of the order of 10 mm(X-direction length)×10 mm (Y-direction length), for example.

In this way, the wireless devices 1C and 1D are provided with theopenings 34 and 35 a in an antenna-opposing region in the second setcasing 30B2 or the electromagnetic shield 35 that is expected to have aneffect on antenna characteristics. Thus, it is possible to reduce theeffect on antenna characteristics caused by the reflection of radiowaves in the antenna-opposing region, and it is possible to suppresschanges in the radiation pattern of the antennas 13. Furthermore, in thewireless device 1C and the wireless device 1D, the behavior (forexample, reflection and diffraction) of radio waves differs according towhether the material is a dielectric or a conductor, and the differencein characteristics depicted in FIG. 7, for example, occurs.

(Second Embodiment)

In the first embodiment, a description was given regarding the casewhere a set casing that is arranged above (Z-axis positive side) thewireless module 10 is a substantially flat plate. In the secondembodiment, it is assumed that a recess is provided in a set casing. Byproviding a recess, the set casing can be arranged closer to thewireless module 10 than in the first embodiment, and the wireless devicecan be made thin.

FIG. 10 is a cross-sectional view depicting a wireless device 1E as afirst exemplary structure of a wireless device in the second embodiment.

In the wireless device 1E, the distance between the antennas 13 and aset casing 30E may be an approximate multiple of λ/2, for example.

In the wireless device 1E, when a distance of approximately λ/2 cannotbe ensured as the distance between the antennas 13 and the set casing30E, the recess 37 is provided in a region in the set casing 30E thatopposes the antennas 13. A distance that is an approximate multiple ofλ/2 is ensured as the distance between the antennas 13 and the bottomsurface 37 a of the recess 37. More specifically, the Z-direction lengthof the gap 40 in FIG. 10 corresponds to the distance between theantennas 13 and the bottom surface 37 a of the recess 37, and is anapproximate multiple of λ/2. It should be noted that the recess 37 is anexample of a recessed section.

According to the wireless device 1E, the recess 37 is provided in theset casing 30E, and the set casing 30E can be arranged as close aspossible to the wireless module 10. Consequently, the wireless device 1Ecan be made thinner. Furthermore, by setting the Z-direction length ofthe gap 40 to be an approximate multiple of λ/2, deterioration ofantenna characteristics can be suppressed as in the first embodiment.

FIG. 11(A) is a cross-sectional view depicting a wireless device 1F as asecond exemplary structure of the wireless device in the secondembodiment, and is an 11(A)-11(A) cross-sectional view of FIG. 11(B).FIG. 11(B) is a plan view depicting an exemplary structure of thewireless device 1F, and depicts the case where the wireless module 10 isviewed from above (Z-axis positive side). Furthermore, in FIG. 11(B),the portion surrounding antennas 13A in the wireless module 10 isdepicted, and the depiction of other portions is omitted.

In FIGS. 11(A) and (B), it is assumed that the antennas 13A are 2×4patch antennas, and radiation directivity according to the antennas 13Ais a direction (Z direction) that is orthogonal to the module substrate3 (see arrow α1). The recess 37 is formed in such a way as to surroundthe antennas 13A, and the distance d2 between the antennas 13A and anend section (side surface 37 b) of the recess 37 is an approximatemultiple of 1/2 of the wavelength λ of a radio wave radiated by theantennas 13A.

It should be noted that, although the corner sections of the recess 37are formed in a rounded manner in FIG. 11(B), the shape of the cornersections of the recess 37 depends on the processing of the set casing30E. For example, the corner sections of the recess 37 would beright-angled when the set casing 30E were processed by way of aright-angle processing method.

According to the wireless device 1F, as a result of the distance betweenthe antennas 13A and the side surface 37 b of the recess 37 being set toan approximate multiple of λ/2, it is possible to suppress the effect ofreflected waves on components that have a direction that follows the X-Yplane from among radio waves radiated from the antennas 13A.

(Third Embodiment)

In the third embodiment, a case is presented where the directivity ofradio waves radiated from an antenna is an inclined direction (adirection offset by a prescribed angle from perpendicular) rather thanbeing perpendicular (Z-axis direction) to the module substrate 3.

FIG. 12(A) is a cross-sectional view depicting a wireless device 1H as afirst exemplary structure of a wireless device in the third embodiment,and is a 12(A)-12(A) cross-sectional view of the wireless device 1H ofFIG. 12(B). FIG. 12(B) is a plan view depicting an exemplary structureof the wireless device 1H, and depicts the case where the wirelessmodule 10 is viewed from above (Z-axis positive side). Furthermore, inFIG. 12(B), the portion surrounding antennas 13B in the wireless module10 is depicted, and the depiction of other portions is omitted.

In the second embodiment, it was assumed that the radiation direction ofradio waves is orthogonal to the module substrate 3, and therefore adescription was given of the case where the bottom surface 37 a or theside surface 37 b in a recess 37 is line-symmetrical with respect to theantennas 13A in the X-Y plane.

In the present embodiment, it is assumed that radio waves are radiatedin an inclined direction from the module substrate 3, namely in adirection that is inclined with respect to the Z direction. For example,in FIGS. 12(A) and (B), it is assumed that the antennas 13B are 3×2patch antennas, and the radiation direction of radio waves according tothe antennas 13B is inclined at a prescribed angle from the Z directionto the X-axis positive direction (see arrow α2).

In the case where the radiation direction of radio waves according tothe antennas 13B is inclined at a prescribed angle from the Z direction,part of the bottom surface 37 a or the side surface 37 b of the recess37H of a set casing 30H that is positioned in the radiation directionhas an effect on antenna characteristics. In the wireless device 1H, thedistance between the part of the recess 37H that is positioned in theradiation direction of radio waves according to the antennas 13B and theantennas 13B is longer than the distance between part of the recess 37Hthat is positioned in a direction other than the radiation direction ofradio waves according to the antennas 13B and the antennas 13B.

For example, in the case where the radiation direction of radio wavesaccording to the antennas 13B is inclined at 45 degrees with respect tothe X-Y plane, the distance d5 between the antennas 13B at theradio-wave radiation side (the right side in FIGS. 12(A) and (B)) andthe side surface 37 b of the recess 37H is, for example, approximately(λ/2)×√2. On the other hand, the distance d6 between the antennas 13B atthe opposite side (the left side in FIGS. 12(A) and (B)) to theradio-wave radiation side and the side surface 37 b of the recess 37His, for example, approximately λ/(2√2). It should be noted that “√X”represents the square root of X.

Furthermore, when it is generalized that the radiation direction ofradio waves according to the antennas 13B is inclined at θ2 degrees withrespect to the X-Y plane, the distance d5 at the radio-wave radiationside and the distance d6 at the opposite side to the radio-waveradiation side are given as follows. It should be noted that “θ2”indicates the radiation angle (directivity angle (angle of elevation))of radio waves according to the antennas 13B, and indicates theradiation angle of radio waves with respect to the X-Y plane.d5=λ/2×(1/sin θ2)d6=λ/2×sin θ2

According to the wireless device 1H, the distance between the antennas13B and the side surface 37 b of the recess 37H is adjusted according tothe radiation direction of the radio waves of the antennas 13B.Consequently, the effect caused by reflected waves of a signal in theside surface 37 b of the recess 37H can be reduced, and deterioration ofantenna characteristics can be suppressed.

FIG. 13(A) is a cross-sectional view depicting a wireless device 1I as asecond exemplary structure of the wireless device in the thirdembodiment, and is a 13(A)-13(A) cross-sectional view of the wirelessdevice 1I of FIG. 13(B). FIG. 13(B) is a plan view depicting anexemplary structure of the wireless device 1I, and depicts the casewhere the wireless module 10 is viewed from above (Z-axis positiveside). Furthermore, in FIG. 13(B), the portion surrounding the antennas13B in the wireless module 10 is depicted, and the depiction of otherportions is omitted. Here, a description is given mainly with regard toportions that are different from the wireless device 1H.

In the wireless device 1H, the case where the rectangular recess 37H isprovided was described as an example. In the wireless device 1I depictedin FIGS. 13(A) and (B), a set casing 30I has a recess 37I that widens inthe radiation direction of the radio waves radiated by the antennas 13B.In other words, as depicted in FIG. 13(B), the recess 37I widens in theX direction and the Y direction, toward the side surface 37 b at theright side (X-axis positive-side end section) of the recess 37I. Thewireless device 1H is configured in such a way that, in order to reducethe effect caused by the radiation of radio waves by the antennas 13B inthe horizontal direction (XY direction), the recess 37I widens as thedistance from the antennas 13B in the XY direction increases.

FIGS. 14(A) and (B) are schematic views depicting an example of aradiation pattern of radio waves according to the antennas 13B in thesecond exemplary structure of the present embodiment. FIG. 14(A) depictsan XZ-direction radiation pattern. In FIG. 14(A), the reference sign α2indicates the radiation direction of radio waves according to theantennas 13B, and the angle θA in FIG. 14(A) indicates the radiationangle (directivity angle (angle of elevation)) of radio waves accordingto the antennas 13B.

FIG. 14(B) depicts a radiation pattern that indicates conical planedirectivity. As depicted in FIG. 15, this conical plane directivityindicates directivity in a plane F1 that is parallel to the substratehorizontal direction (XY direction) at the radiation angle θA of radiowaves according to the antennas 13B.

The angle θB in FIG. 14(B) indicates an angle at which line segments L1and L2 (see FIG. 13(B)) that define a range in which antenna gainaccording to the antennas 13B becomes approximately 1/4 in the XYdirection are formed, with the central section of all of the antennas13B being the starting point. The angle formed between a side surface 37b 3 and a side surface 37 b 4, which are depicted in FIG. 13(B) and areformed in such a way that the recess 37I widens, is formed so as to besubstantially coincident with the angle θB.

In FIGS. 14(A) and (B), radiation patterns P1 and P2 indicate radiationpatterns of radio waves according to the antennas 13B.

Consequently, the area of a side surface 37 b 1 of the recess 37I thatis present in the radiation direction of radio waves is formed largerthan the area of a side surface 37 b 2 of the recess 37I that is presentat the opposite side to the radiation direction of radio waves. Itshould be noted that the side surface 37 b of the recess 37I may be aflat surface or a curved surface.

According to the wireless device 1I, the recess 37I is formed to widenin the radiation direction of radio waves according to the antennas 13B,and therefore the effect of reflected waves in the recess 37I can besuppressed. Consequently, deterioration of antenna characteristics canbe suppressed.

(Fourth Embodiment)

In the second and third embodiments, descriptions have been givenregarding the case where the bottom surface of a recess in a set casingis formed parallel with the front surface (outer peripheral surface) ofthe set casing. In the fourth embodiment, a description is givenregarding the case where the bottom surface of a recess in a set casingis inclined.

FIG. 16(A) is a cross-sectional view depicting a wireless device 1J as afirst exemplary structure of a wireless device in the fourth embodiment,and is a 16(A)-16(A) cross-sectional view of the wireless device 1J ofFIG. 16(B). FIG. 16(B) is a plan view depicting an exemplary structureof the wireless device 1J, and depicts the case where the wirelessmodule 10 is viewed from above (Z-axis positive side). Furthermore, inFIG. 16(B), the portion surrounding the antennas 13B in the wirelessmodule 10 is depicted, and the depiction of other portions is omitted.

In the case where the radiation of radio waves from the antennas 13B isinclined (not perpendicular) with respect to the module substrate 3,when the bottom surface of the recess in the set casing is formedparallel to the module substrate 3, radio waves are incident at anincline with respect to the bottom surface of the recess. In this case,the directivity of the antennas is disturbed due to refraction in thebottom surface of the recess.

As depicted in FIG. 16(A), in the wireless device 1J, a bottom surface37 c of a recess 37J of a set casing 30J is inclined so as to besubstantially perpendicular with respect to the radiation direction (thedirection of arrow α3) of radio waves according to the antennas 13B. Inthis case, the refraction of the radio waves radiated from the antennas13B is small, and changes in the radiation pattern can be reduced.

Furthermore, the longest distance d7 that follows the radiationdirection of radio waves according to the antennas 13B between the topsurface of the wireless module 10 and the bottom surface 37 c of therecess 37J is, for example, an approximate multiple of λ/2. Thus, theeffect of the reflection of radio waves by the recess 37J can besuppressed.

In this way, the wireless device 1J has the bottom surface 37 c of therecess 37J as a tapered surface that is substantially orthogonal to theradiation direction of radio waves according to the antennas 13B. Thus,the reflection of radio waves in a direction that does not follow theradiation direction of radio waves in the recess 37J is suppressed, anddeterioration of antenna characteristics can be suppressed.

FIG. 17(A) is a cross-sectional view depicting a wireless device 1K as asecond exemplary structure of the wireless device in the fourthembodiment, and is an 17(A)-17(A) cross-sectional view of the wirelessdevice 1K of FIG. 17(B). FIG. 17(B) is a plan view depicting anexemplary structure of the wireless device 1K, and depicts the casewhere the wireless module 10 is viewed from above (Z-axis positiveside). Furthermore, in FIG. 17(B), the portion surrounding the antennas13B in the wireless module 10 is depicted, and the depiction of otherportions is omitted.

In the wireless device 1J, an example was given in which the bottomsurface 37 c of the recess 37J was inclined in a uniform manner;however, as depicted in FIG. 17(A), a bottom surface 37 d of a recess37K may be divided into several portions and inclined, and bottomsurfaces 37 d 1 to 37 d 3 may be formed. In the FIGS. 17(A) and (B), forexample, the antennas 13B are arranged in the X direction, recesses 37K1to 37K3 are divided corresponding to each antenna element, and eachdivided bottom surface 37 d 1 to 37 d 3 is inclined.

Furthermore, the longest distance d8 that follows the radiationdirection of radio waves according to the antennas 13B between the topsurface of the wireless module 10 and the bottom surfaces 37 d of therecesses 37K is, for example, an approximate multiple of λ/2. Thus, theeffect of the reflection of radio waves by the recesses 37K can besuppressed.

Thus, compared to the case where the bottom surface 37 c of the recess37J is inclined in a uniform manner, it is possible for radio wavesradiated from each antenna element in the antennas 13B to be incident ina substantially perpendicular manner to each bottom surface 37 d 1 to 37d 3. Furthermore, because there are inclines corresponding to eachantenna element, a set casing 30K can be made thicker compared to whenthe bottom surface 37 c is inclined in a uniform manner, and thestrength of the set casing 30K can be improved.

In this way, the wireless device 1K has the bottom surface 37 d of therecess 37K that is substantially orthogonal to the radiation directionof radio waves according to the antennas 13B, corresponding to eachantenna element. Thus, the reflection of radio waves in a direction thatdoes not follow the radiation direction of radio waves in the recess 37Kis suppressed, and deterioration of antenna characteristics can besuppressed. Furthermore, the set casing 30K can be strengthened.

FIG. 18(A) is a cross-sectional view depicting a wireless device 1L as athird exemplary structure of the wireless device in the fourthembodiment, and is an 18(A)-18(A) cross-sectional view of the wirelessdevice 1L of FIG. 18(B). FIG. 18(B) is a plan view depicting anexemplary structure of the wireless device 1L, and depicts the casewhere the wireless module 10 is viewed from above (Z-axis positiveside). Furthermore, in FIG. 18(B), the portion surrounding the antennas13B in the wireless module 10 is depicted, and the depiction of otherportions is omitted.

In the FIGS. 18(A) and (B), a description is given mainly with regard tothe differences with the wireless device 1J depicted in FIGS. 16(A) and(B), and a description regarding the configuration that is the same asthe wireless device 1J is omitted.

In the wireless devices 1J and 1K, examples were given in which thebottom surfaces 37 c and 37 d of the recesses 37J and 37K were inclined.In the wireless device 1L, as depicted in FIG. 18(A), an outerperipheral surface 30 l on the opposite side to the bottom surface 37 cof the recess 37J of a set casing 30L is also inclined. For example, theouter peripheral surface 30 l of the set casing 30L and the bottomsurface 37 c of the recess 37J are formed substantially parallel.

According to the wireless device 1L, the radiation direction of radiowaves is substantially orthogonal with respect to the outer peripheralsurface and the inner peripheral surface of the set casing 30L, andtherefore the refraction of radio waves when radio waves pass from theinside of the set casing 30L to the outside can be reduced. Furthermore,the set casing 30L can be made thin, and therefore the electrical lengthwhen radio waves pass through the set casing 30L becomes shorter, andchanges in the radiation direction of radio waves according to the setcasing 30L can be suppressed.

It should be noted that the present disclosure is not limited to theconfigurations of the aforementioned embodiments, and any kind ofconfiguration can be applied as long as the configuration is such thatthe functions indicated by the scope of the patent claims or thefunctions of the configurations of the present embodiments are able tobe achieved.

For example, in the aforementioned embodiments, patch antennas weremainly assumed as the antennas; however, other antennas may be used.

Furthermore, the wireless devices 1J and 1K are configured in such a waythat the distances between the antennas and a side surface of the recessdiffer depending on whether it is the radio-wave radiation side or theopposite side to the radio-wave radiation side (for example, distancesd5 and d6); however, these distances may be the same.

Furthermore, the embodiments and the exemplary structures have beendescribed using a common wireless module 10; however, another knownwireless module 10 may be used.

It should be noted that the embodiments or the exemplary structures ofthe wireless devices may be combined as appropriate.

(Summary of an Embodiment of the Present Disclosure)

A first wireless device of the present disclosure comprises:

a substrate;

a wireless module that is mounted on the substrate and has an antennaunit; and

a casing that accommodates the substrate and the wireless module,

wherein the wireless device has a gap from the antenna unit toward thecasing, and the gap has a length that is an approximate multiple of ahalf-wavelength of a radio wave corresponding to a communicationfrequency of the antenna unit.

A second wireless device of the present disclosure is the first wirelessdevice,

wherein the casing includes an antenna-opposing region that opposes theantenna unit, and a non-antenna-opposing region that is a region otherthan the antenna-opposing region,

and the antenna-opposing region is formed from a material that has alower relative permittivity, or a smaller dielectric loss tangent, thanthe non-antenna-opposing region.

A third wireless device of the present disclosure is the first or secondwireless device,

wherein the third wireless device has a gap between the antenna unit andthe casing, and the gap has a length that is an approximate multiple ofa half-wavelength of a radio wave corresponding to the communicationfrequency of the antenna unit.

A fourth wireless device of the present disclosure is the first orsecond wireless device,

wherein the fourth wireless device further comprises a first memberbetween the antenna unit and the casing,

and has a gap between the antenna unit and the first member, and the gaphas a length that is an approximate multiple of a half-wavelength of aradio wave corresponding to the communication frequency of the antennaunit.

A fifth wireless device of the present disclosure is the first or secondwireless device,

wherein the fifth wireless device further comprises a first memberbetween the antenna unit and the casing,

and, when a distance between the antenna unit and the first member isless than a half-wavelength of a radio wave corresponding to thecommunication frequency of the antenna unit, the first member has anopening in a region, which opposes the antenna unit.

A sixth wireless device of the present disclosure is the first wirelessdevice,

wherein the casing has a recessed section in a region that opposes theantenna unit,

and a distance between the antenna unit and the recessed section is alength that is an approximate multiple of a half-wavelength of a radiowave corresponding to the communication frequency of the antenna unit.

A seventh wireless device of the present disclosure is the sixthwireless device,

wherein a distance between the antenna unit and a bottom surface of therecessed section is a length that is an approximate multiple of ahalf-wavelength of a radio wave corresponding to the communicationfrequency of the antenna unit.

An eighth wireless device of the present disclosure is the sixth orseventh wireless device,

wherein a distance between the antenna unit and a side surface of therecessed section is a length that is an approximate multiple of ahalf-wavelength of a radio wave corresponding to the communicationfrequency of the antenna unit.

A ninth wireless device of the present disclosure is any one of thesixth to eighth wireless devices,

wherein a distance between the antenna unit and a first side surface ofthe recessed section that corresponds to a radiation direction of theradio wave is longer than a distance between the antenna unit and asecond side surface of the recessed section that corresponds to adirection opposite to the radiation direction of the radio wave.

A tenth wireless device of the present disclosure is any one of thesixth to ninth wireless devices,

wherein an area of the first side surface of the recessed section thatcorresponds to the radiation direction of the radio wave is larger thanan area of the second side surface of the recessed section thatcorresponds to the direction opposite to the radiation direction of theradio wave.

An eleventh wireless device of the present disclosure is any one of thesixth to tenth wireless devices,

wherein the bottom surface of the recessed section of the casing has atapered surface that is substantially orthogonal to the radiationdirection of the radio wave.

A twelfth wireless device of the present disclosure is the eleventhwireless device,

wherein the antenna unit includes a plurality of antenna elements,

and the bottom surface of the recessed section of the casing has atapered surface that is substantially orthogonal to a radiationdirection of the radio wave from each of the antenna elements.

A thirteenth wireless device of the present disclosure is the eleventhor twelfth wireless device,

wherein an outer peripheral surface of the casing has a tapered surfacethat follows the bottom surface of the recessed section.

INDUSTRIAL APPLICABILITY

An aspect of the present disclosure is useful in a wireless device orthe like that suppresses deterioration of antenna characteristics andcan be made thin.

REFERENCE SIGNS LIST

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L wireless device

10 wireless module

20 set substrate

30, 30A, 30B1, 30B2, 30E, 30H, 30I, 30J, 30K, 30L set casing

3 module substrate

3 a metal layer

3 b dielectric layer

3 c GND layer

3 d wiring layer

8, 9 LSI

11 GND pattern

13, 13A, 13B antenna

17, 36 signal via

19, 33 GND via

21 a, 21 b, 21 c, 21 d pad

22 a, 22 b, 22 c, 22 d solder ball

27 mold section

31 antenna-opposing region

32 other region

34 opening

35 electromagnetic shield

35 a opening

37, 37H, 37I, 37J, 37K, 37K1, 37K1, 37K2, 37K3 recess

37 a, 37 c, 37 d, 37 d 1, 37 d 2, 37 d 3 bottom surface

37 b, 37 b 1, 37 b 2, 37 b 3, 37 b 4 side surface

40 gap

The invention claimed is:
 1. A wireless device comprising: a substrate;a wireless module that is mounted on the substrate and includes anantenna unit; and a casing that accommodates the substrate and thewireless module and has a recessed section in a region that opposes theantenna unit, wherein a distance between the antenna unit and therecessed section is a length that is an approximate multiple of ahalf-wavelength of a radio wave corresponding to the communicationfrequency of the antenna unit, and a distance between the antenna unitand a first side surface of the recessed section that corresponds to aradiation direction of the radio wave is longer than a distance betweenthe antenna unit and a second side surface of the recessed section thatcorresponds to a direction opposite to the radiation direction of theradio wave.
 2. The wireless device according to claim 1, wherein thecasing includes an antenna-opposing region that opposes the antennaunit, and a non-antenna-opposing region that is a region other than theantenna-opposing region, and the antenna-opposing region is formed froma material that has a lower relative permittivity, or a smallerdielectric loss tangent, than the non-antenna-opposing region.
 3. Thewireless device according to claim 1, further comprising, a first memberprovided between the antenna unit and the casing such that a gap isprovided between the antenna unit and the first member, the gap having alength that is an approximate multiple of a half-wavelength of the radiowave.
 4. The wireless device according to claim 1, further comprising, afirst member provided between the antenna unit and the casing, wherein adistance between the antenna unit and the first member is less than ahalf-wavelength of the radio wave, and the first member has an openingin a region, which opposes the antenna unit.
 5. The wireless deviceaccording to claim 1, wherein a distance between the antenna unit and abottom surface of the recessed section is a length that is anapproximate multiple of a half-wavelength of the radio wave.
 6. Thewireless device according to claim 1, wherein a distance between theantenna unit and a side surface of the recessed section is a length thatis an approximate multiple of a half-wavelength of the radio wave. 7.The wireless device according to claim 1, wherein a bottom surface ofthe recessed section of the casing has a tapered surface that issubstantially orthogonal to a radiation direction of the radio wave. 8.The wireless device according to claim 7, wherein the antenna unitincludes a plurality of antenna elements, and a bottom surface of therecessed section of the casing has a tapered surface that issubstantially orthogonal to a radiation direction of a radio wave fromeach of the antenna elements.
 9. The wireless device according to claim7, wherein an outer peripheral surface of the casing has a taperedsurface along the bottom surface of the recessed section.
 10. A wirelessdevice comprising: a substrate; a wireless module that is mounted on thesubstrate and includes an antenna unit; and a casing that accommodatesthe substrate and the wireless module and has a recessed section in aregion that opposes the antenna unit, wherein a distance between theantenna unit and the recessed section is a length that is an approximatemultiple of a half-wavelength of a radio wave corresponding to thecommunication frequency of the antenna unit, and an area of a first sidesurface of the recessed section that corresponds to the radiationdirection of the radio wave is larger than an area of a second sidesurface of the recessed section that corresponds to a direction oppositeto the radiation direction of the radio wave.
 11. The wireless deviceaccording to claim 10, wherein the casing includes an antenna-opposingregion that opposes the antenna unit, and a non-antenna-opposing regionthat is a region other than the antenna-opposing region, and theantenna-opposing region is formed from a material that has a lowerrelative permittivity, or a smaller dielectric loss tangent, than thenon-antenna-opposing region.
 12. The wireless device according to claim10, further comprising, a first member provided between the antenna unitand the casing such that a gap is provided between the antenna unit andthe first member, the gap having a length that is an approximatemultiple of a half-wavelength of the radio wave.
 13. The wireless deviceaccording to claim 10, further comprising, a first member providedbetween the antenna unit and the casing, wherein a distance between theantenna unit and the first member is less than a half-wavelength of theradio wave, and the first member has an opening in a region, whichopposes the antenna unit.
 14. The wireless device according to claim 10,wherein a distance between the antenna unit and a bottom surface of therecessed section is a length that is an approximate multiple of ahalf-wavelength of the radio wave.
 15. The wireless device according toclaim 10, wherein a distance between the antenna unit and a side surfaceof the recessed section is a length that is an approximate multiple of ahalf-wavelength of the radio wave.
 16. The wireless device according toclaim 10, wherein a bottom surface of the recessed section of the casinghas a tapered surface that is substantially orthogonal to a radiationdirection of the radio wave.
 17. The wireless device according to claim16, wherein the antenna unit includes a plurality of antenna elements,and a bottom surface of the recessed section of the casing has a taperedsurface that is substantially orthogonal to a radiation direction of aradio wave from each of the antenna elements.
 18. The wireless deviceaccording to claim 16, wherein an outer peripheral surface of the casinghas a tapered surface along the bottom surface of the recessed section.